Strainer for wells



June 21 1938. L. A. LAYNE I v 2,120,983

STRAINER FOR WELLS Filed Sept. 25, 1936 2 Sheets-Sheet l INVENTOR LESLIEALAYNL BY 09% ATTORNEYS.

2 Sheets-Sheet 2'" 1.. A. LAYNE STRAINER FOR WELLS Filed Sept. 25, 1936, v

June 21, 1938.

Patented June 21, 1938 uru'rlszov STATES PATENT OFFFICEI- 2,120,983 STRAINER FOR WELLS Leslie A. Layne, Houston, Tex.

Application September 25, 1936, Serial No. 102,501

4 Claims. (01. 166-8) The invention relates to a means and method of controlling an inlet flow of fiuidthrough the strainer in wells in order to extend the productive period of both the strainer and the well. In theproduction of fluids from wells, and particularly of oil and gas which are generally located in a porous or granular formation,- it is the practice to provide a strainer or screen in order to hold back the granular formation. 10 Such strainers are usually made to a particular gauge or size opening slightly less than the size of the sand or grains in which the desired fluid is found so that the fluid could drain into the well through the strainer and the major portion 15 of the granular material excluded from the well. In the production of oil and gas and particularly where large volumes of fluid pass through the screen or where high pressure existed it has not been uncommon for the abrasive effect of the 20 smaller particles of sand passing through the strainer to quickly destroy the gauge or size opening of the strainer, so that it no longer excluded the size of grains which it had been designed to exclude with the result that the well soon became 25 clogged or sanded with sediment.

The present invention concerns itself with providing a screen or strainer wherein the volume of flow is controlled by one set of openings or orifices and the gauge of the screen or strainer which determines the size of the grains which may or may not pass'through the strainer will be controlled by another set ofopenings or orifices. This arrangement permits the rate of flow through the openings which form the gauge of the strainer to be controlledto such a. rate of flow as will prevent abrasion and wearing away of the gauge of the strainer by controlling'the rate of flow at the ,volume orifices.

' It is one of the objects of \the invention to provide a strainer or screen for wells wherein two sets of independent openings are provided,

one to control the volume of flow, and the'other toexclude undesirable materials of greater than a predetermined size.

Another object of the invention is to provide the gauge of a strainer in a well bore by controlling the velocity flow therethrough.

Another object of the invention is to provide a strainer which is so constructed and arranged thatthe velocity of flow therethrough will be 5 constant.

' Another object of the invention is to provide a strainer which is so constructed and arranged that the velocity of flow will be increased as it progresses through the strainer.

Another object of the invention is to provide a strainer arrangement wherein there is a frame and strainer portion wherein the strainer area is so designed relative to the openings through the frame that the area of any opening in the frame is slightly less than the area of the strainer portion, which is tributary thereto. Another object is to equalize the flow of liquid through the gauge opening by removing the control of the volume flow therefrom.

Another object of the invention isto preven the clogging of a strainer screen by providing the greatest velocity of flow in the inside thereof. Another object of the invention is to reduce the rate of flow at the gauge area of a strainer 26 so that there will be a deposit of granular material about the opening to form a filter bed.

Another object of the invention is to provide a, control orifice of such a size as compared to tion is considered in connection with the accompanying drawings, wherein:

Fig-l is a side elevation of a strainer constructed in accordance with the present invention and also the formation arranged thereabout.

Fig. 2 is an enlarged view of a strainer with certain portions broken away to illustrate the construction. Fig. 3 is a magnified view of a side elevation of the strainer assembly. A

Fig. 4 is a section taken on the line 4-4 of Fig. 3 and looking in the direction of the arrows.

Fig. 5 is a magnified vertical section illustrating the arrangement of openings and the for mation of the filter bed.

Fig. 6 shows a side elevation of a particular form of strainer wire used to obtain a constant velocity flow.

Figs. 7 and 8 are sections taken on the lines 'I'I and 8--8, respectively, of Fig. 6 to show the cross section of the strainer wire.

Fig. 9 shows another form of strainer wire which may be used. In Fig. 1 the well bore is indicated generally at 2 and inserted therein is can either flow. or be pumped to the surface.

The porous or granular formation 8 about the strainer gradually moves to the position shown in Fig. 1 where it accumulates about the strainer.

The structure so far described is old and well 2 known in the art and sets forth what is a standard practice in the straining of sandfrom de- The grains of sand II) which make up the formation 8 are more or less uniform in size in any particular formation, various formations having, of course, different sized grains. It is therefore the practice to'determine'thesize'of f the grains and tothen make the gauge of the openings 6 such that they a're'slightly smaller than the predominant'size of the grain from which the fluid is to be strained. -In this'manner the major portion of "sand is excluded and the fluid and finer particles of sand pass'into the screen and out'through the'well. The entrance are not excluded by this strainer-occurs at a high rate of speed because with the'strainers used in the past thegauge opening 6 was also the control opening which determined the rate of flow through the strainer. In other words a single opening wasused to control the volume of flow and to also determine the gauge of the strainer.

Necessarily, the size of the opening would become enlarged due to the abrasive action of sand traveling at a high rate of speed and being controlled as to its rate of flow by that same opening. The result of this was the enlargement of the gauge to such an extent that those grains of sand which were intended tobe excluded were shortly permitted to enter the strainer with the resultant of clogging the strainer and sanding up of the well, it being understood that it is the present practice to have the opening in the frame or foundation pipe such as 4 of a greater area than the openings about the wrapping of wires such as the opening 6. These openings were merely provided for'the entrance of fluid afterit had passed the gauge opening 6.; The

pipe was-therefore used for no other purpose 1 than to support the strainer wire.

The present invention contemplates employing this frame for the strainer wire for another pur pose; namely, to control the rate offlow through the strainer and by'so doing to-reduce the rate -of flow at the strainer opening where the gauge is to be maintained so that the abrasive action thereon would bematerial ly reduced and any abrasion would occur at the control orifice rather than at the gaugeopeningl To accomplish this such a strainer is illustrated generallyin Fig. '2, but it is to be specifically understood that the arrangement and the construction of the strainer may be' varied so long as it embodies the principle of providing a set of control orifices and a set of gauge openings, eachof which performs its independent function.

In Fig. 2 a pipe I2 is illustrated as having been provided with a plurality of slots I3. These slots may be of any desired length, width or spacing relative to each other in order to obtain the desired inlet area. Slots have been provided because of the fact that they are of uniform area along the axis of the pipe and in-this manner they can be spaced relative to each other so that the area of these openings with respect to the gauge openingsbetween the wires can'be controlled.

While a pipe has been shown and is herewith described, it isto be understood that any desired type of frame or support for the strainer wire I5 can be provided.- The strainer wire may take any configuration in cross section so long as the gauge of opening I6 between the Wires is maintained. I

In Fig. 3 a broken elevation is shown in which I3-is illustrated beneath the strainer;

the slot wire I5. A keystone. shape wire has been illustrated because this is one of the standard types of wire in general use, but the wire may take different configurations as will be later-explained.

In Fig. 3 the gauge opening I6 is shown as passing transversely across the slots I3 and it seems obvious that certain increments of the In other words, taking the lower opening I6 in Fig. 3 there will be. a of these small particles of sand or gravel which length of the opening I6 which will extend from a point midway between any two of the slots I3 and which is equal to the distance between center lines of any two adjacent slots. 1

In Fig. 3 the length of the opening I6 which will be tributary to the center slot I3 is that distance between the points I8 and I9 measuring across the drawings, whereas the vertical length of the slot I3 which will receive the flow from this tributary area will have the length of"theslots between the points 20 and 2'I measured.

up and down on Fig. 3 of the-drawings.

Thus, the size of an increment of the slot which is of an area equal to" the width of the;

slot by the distance between the points 20 and 2| willbe made of such a size that it will be slightly less than the area of the opening I6 faces 22 of the wire will be materially reduced. This naturally has a tendency to maintain the gauge of the opening I6 for a materially greater length of time because any very slight wear on the opening 16 mmgesrnegau thereof," whereas the wall of the opening lfl has a substantially-greater amount ofmetal present been cause of the greater depth'of 'the opening l3,.

as seen in Fig. 4, when compared with'the 'nansmall row opening I6 which presents but a very amountof metal-to resist wear. v 1

The foregoing explanation "is -merely a,dei tailedanalysis of the operationvof the-strainer? at any particular increment ofsOmeparticular.

slot and a particular'portion of the: gauge opening which is tributary thereto, butserves :toqex-;=, plain that the wear will be taken at sucha'loca-y tion that the gauge opening'may bemaintained;

such as 25.

jected to little or no abrasion due to the passing of fine particles of sand.

The arrangement of the pipe and wire is merely illustrative because the invention may. be applied to other types of screen.

In Fig. an enlarged sectional view is shown in which the vertical increment of the slot I3 is shown between the points 20 and 2E, whereas the transverse increment of the gauge opening I6 is shown between points I8 and I9 in Fig. 4.

In Fig. 5 the formation of the filter bed made up of the gravel Ill has been illustrated, but it will be particularly noted that closely adjacent each of the openings I6 there has been an accumulation of larger particles of sand or gravel These larger particles have accumulated because of the fact that the finer particles from among'them have passed through the opening I6 in the original washing and de- I velopment of the well.

The accumulation of these coarser particles which are held out by the gauge of the opening I6 gradually settle together and form an accumulation as seen in Fig. 5 which, because of the reduced velocity of the flow through the opening I6 forms a barrier for the finer particles of sand such as 26 so that a filter bed having a gradual gradation of particles will occur. After this filter bed has once been formed there will be little or no flow of abrasive through the opening I6 and then when wear does occur on the opening I6 there will have been a filter bed formed as to prevent the inflow of the finer particles. On the other hand, if, during the initial flow, the opening I6 had ben subjected to wear then the larger particles such as 25 would have entered the strainer and the gauge cf the strainer would have been so much enlarged that it would not restrain the size of grain which it had been designed to exclude. It seems obvious therefore that a method of formng a filter bed has been provided by controlling the flow of fiuid at the gauge opening until such time as the filter bed has been formed and that this is accomplished by utilizing a separate control orifice such as the orifice I3 in the frame or body of the strainer.

In some instances it may be desirable to have a uniform rate of flow of fluid from the gauge opening it in between the adjacent wrappings of wire as well as through the control orifice I 3.

If this is desired a special type of wire may be provided such as seen in Figs. 6 and '7. Fig. 6

is a back side view of the wire and showing the face 22 which controls the gauge on the far side, whereas the inside shoulder and face of the wire 30, instead of being of a uniform width, gradually varies in width from the maximum at 3| to the minimum shown at 32. The length of this tapered portion whichis illustrated generally at 33 will be equal to one-half of the distance between center lines of the .slots It so that the area 32 of minimum width will be directly over the center line of an orifice I3,

whereas the maximum width area at M will be over a line midway between the center lines of two adjacent slots I3. The taper of the portion 33 is so designed that it'gradually increases in proportion to the inflow from the gauge opening I6 which is of course of uniform width. In this manner all of the fiuid will fiow at a uniform rate, regardless of which point in the increment in the opening I6 it may make its entry.

In Fig. 8 a wire I5 of uniform cross section has been shown so that a gauge opening I6 of material width is provided. With an opening of this type of course the slot It may be varied in order to ,carry out the function hereinbefore expressed.

Fig. 9 shows a wire I5 having lugs 40 on one side thereof so as to serve as spacers if that type of strainer wire is desired. This forms a definite and independent inlet area for each pipe opening so as to equalize the fiow.

The type of strainer here disclosed can be originally made up of a somewhat coarser gauge than ordinary type strainer because sand cutting and wear on the gauge openin'g is eliminated."

The equalizing of the fiow of fluid through the gauge opening also tends to reduce the rate of flow through any particular part of the opening such as directly over the control orifice. This in turn results in the forming of a much better filter bed and an even pull on the formation so that the sand is not jammed against the strainer and the productive life of the well is materially increased.

Broadly, the invention contemplates the control of the volume through an orifice which can be subjected to a. material amount of wear and which orifice will in turn control the rate of flow through the gauge opening which serves the purpose of determining the size of particles which may pass therethrough. By designing and proportioning the parts in accordance with the foregoing it seems clear thatany particular size of sand may be strained and a. proper filter bed formed about the strainer before the gauge of wire is destroyed.

What is claimed is:

1. A strainer including a wire wrapping having a helical strainer area between the wrappings, a support for the wire having drain openings of slotted configuration through which the fiow from the strainer area will pass, the size of the exposed portion of each opening in the support between adjacent layers of wire being less than the strainer area which serves asa tributary therefor so that velocity of the fluid at the support will be greater than the velocity of the fluid entering between the wire wrappings.

2. A well strainer including a support, slots therein for the entry of fluid from the well, and a strainer structure in close contact over said support, a plurality of independent strainer areas in said structure, the size of the exposed effective areas of each of said slots being such that they are less than the total area of the independent strainer areas that are tributary thereto.

3. In a well strainer comprising a slotted pipe pipe and wire wrapping thereon, an increment of structure to control and gauge the flow of fiuid comprising a control orifice created by the uncovered area of a slot between two adjacent edges of contiguous wrappings of wire, and a gauge opening tributary to said control orifice and of greater area than said orifice which is created by the space between the outer edges of said contiguous wrappings of wire and of a length equal to the distance between centers of two adjacent the wider portion outward, the gauge of the strainer being determined by the spacing of the wider edges of the adjacent wrappings of wire, the inside face of the wire being in close contact with the periphery of the pipe and overlying por- 7I tions of said slots so as to divide each slot into a plurality of vertically spaced eifective control areas defined by. the width of the slot and the spacing of the inner adjacent edges of the narrower portions of the keystone wire, a strainer area which is tributary to each control area which is formed of a width equal to the gauge of the strainer due to the spacing of the wrappings of wire and of a length between the center lines intermediate to adjacent slots, the strainer area being greater than the control area to which it is tributary so that the control area determines the volume of flow and the strainer area determines the size of foreign matter carried by the fluid being strained which shall not pass so that the rate of flow is controlled by said control area.

LESLIE A. LAYNE. 

